A bad night's sleep may make people buy more unhealthy foods the next day, a new study suggests. People who were deprived of one night's sleep purchased more calories and grammes of food in a mock supermarket on the following day, researchers said.
Sleep deprivation also led to increased blood levels of ghrelin, a hormone that increases hunger, on the following morning.
However, there was no correlation between individual ghrelin levels and food purchasing, suggesting that other mechanisms - such as impulsive decision making - may be more responsible for increased purchasing.
Researchers in Sweden were curious as to whether sleep deprivation may impair or alter an individual's food purchasing choices based on its established tendency to impair higher-level thinking and to increase hunger.
"We hypothesised that sleep deprivation's impact on hunger and decision making would make for the 'perfect storm' with regard to shopping and food purchasing – leaving individuals hungrier and less capable of employing self-control and higher-level decision-making processes to avoid making impulsive, calorie-driven purchases," said first author Colin Chapman, of Uppsala University.
On the morning after one night of total sleep deprivation, as well as after one night of sleep, Chapman, along with Christian Benedict, and their colleagues, gave 14 normal-weight men a fixed budget (approximately USD 50).
The men were instructed to purchase as much as they could out of a possible 40 items, including 20 high-caloric foods and 20 low-calorie foods.
The prices of the high-caloric foods were then varied to determine if total sleep deprivation affects the flexibility of food purchasing.
Before the task, participants received a standardised breakfast to minimise the effect of hunger on their purchases. Sleep-deprived men purchased significantly more calories and grammes of food than they did after one night of sleep.
The researchers also measured blood levels of ghrelin, finding that the hormone's concentrations were higher after total sleep deprivation; however, this increase did not correlate with food purchasing behaviour.
"Our finding provides a strong rationale for suggesting that patients with concerns regarding caloric intake and weight gain maintain a healthy, normal sleep schedule," said Chapman.
The study was published in the journal Obesity.